1. Field of the Invention
The present invention relates to a recording apparatus, for example, of inkjet type.
2. Discussion of Related Art
As a kind of recording apparatus, there is known an inkjet type recording apparatus for performing a recording operation. During the recording operation, an inkjet head unit is caused to eject recording materials (ink droplets) toward a recording medium, while a carriage carrying the head unit is moved such that the head unit is moved relative to the recording medium with a predetermined spacing distance therebetween being maintained.
As such an inkjet type recording apparatus, there is a recording apparatus in which a head driver unit mounted on the carriage is arranged to receive various data signals such as drive data signals (recording data signals) and drive waveform signals that are outputted from a main circuit disposed in a stationary main body of the apparatus. The inkjet head unit (hereinafter referred to as “recording head unit”) is operated by the head driver unit, so as to eject the ink droplets through a plurality of nozzles formed in the head unit.
In the inkjet type recording apparatus, for performing a recording operation with gradation control, a plurality of drive waveform signals having respective different drive waveforms have to be available so that the recording material can be ejected as an ink droplet that is variable in its size. Further, for reducing a peak value of electric power consumed by the recording head unit and for avoiding a so-called “cross talk” between adjacent ink chambers of the recording head unit, the drive waveform signals supplied for ink ejections through respective nozzles arranged in each region or row have to be variable so as to be different from each other. Further, where a color recording operation is performed by using a plurality of different recording materials, there is a requirement of recording with the drive waveform signals having respective waveforms suitable for characteristics of the respective color inks. Consequently, the required number of kinds of drive waveform signals are increased for satisfying the above requirements. The increase in the number of kinds of drive waveform signals leads to increase in the number of signal wires required for supplying the drive waveform signals to the drive circuits of the head driver unit.
The increase of the number of the signal wires is disadvantageous in view of cost and maintenance performance. Particularly, where a flexible flat cable is used for transmitting the signals from the main circuit disposed in the stationary main body to the head driver unit carried by the carriage, the flexible flat wire has a width inevitably increased by the increased number of the signal wires, thereby necessitating a complicated disposition of the flexible flat cable and even increasing a load exerted on the carriage moved relative to the stationary main body.
In view of the above-described problems, there have been made various attempts to reduce the number of the signal wires for transmitting the drive waveform signals from the main circuit to the head driver unit. For example, there was proposed an arrangement, as disclosed in JP-2000-158643A, in which waveform-related data (e.g., data representative of pulse width) required for generation of drive waveform signals are serially transmitted to each of drive-waveform-signal generator circuits disposed in the recording head unit prior to a recording operation, and the drive waveform signals are generated based on the waveform-related data by the drive-waveform-signal generator circuits upon initiation of the recording operation.
In the above-described proposed arrangement, the number of the signal wires for transmitting the drive waveform signals from the main circuit to the head driver unit can be made smaller than in the conventional arrangement. However, the plurality of drive-waveform-signal generator circuits as extra components are required for the generations of the respective different drive waveform signals, whereby the recording head unit is inevitably increased in weight.